A touch display screen, as an input media, is a simplest and convenient human-computer interaction method at present, and thus, touch display screens are applied to various electronic products increasingly. Based on different working principles and media for transmitting information, the products having touch screens can be classified into four kinds as follows: an infrared touch screen, a capacitive touch screen, a resistive touch screen, and a surface acoustic wave touch screen; wherein the capacitive touch screen becomes a current mainstream touch screen technology for its advantages such as long lifespan, high transmittance, capable of supporting multi-touch. The capacitive touch screen includes a surface capacitive touch screen and a projected capacitive touch screen, wherein the projected capacitive touch screen also can be classified into a self-capacitive touch screen and a mutual capacitive touch screen. A self capacitive touch structure has a higher touch inductive accuracy and a higher signal-to-noise ratio, thereby being preferred by all panel manufacturers.
At present, the self capacitive touch structure uses a self capacitive principle to realize detecting finger touch positions, in specific: a plurality of self capacitive electrodes that are disposed in the same layer and insulated with each other are disposed in the touch structure, when a human body does not touch the screen, a capacitance value born by each self capacitive electrode is a fixed value, and when the human body touches the screen, a capacitance born by the self capacitive electrode corresponding to the touch position is a sum of a fixed value and a human body capacitance. A touch control detection chip may judge the touch position by detecting a capacitance value change of each self capacitive electrode in a touch period.
Regarding the self capacitive in-cell touch screen, in general, touch control inductive electrodes and metal connection lines in a touch screen structure are directly disposed on an array substrate or a filter substrate. FIG. 1 is a structure diagram of an array substrate having a touch screen structure. As shown in FIG. 1, the array substrate includes a glass substrate 1 and a first metal layer 2, an insulating layer 3a, a second metal layer 4, a second insulating layer 3b, a common electrode layer 5, a third insulating layer 3c, a third metal layer 6, a fourth insulating layer 3d and a pixel electrode layer 7 that are laminated on the glass substrate 1 in sequence. Wherein, a plurality of scan lines are disposed in the first metal layer 2, a plurality of data lines are disposed in the second metal layer 4, and the scan lines and the data lines are vertical to each other in a wiring direction. Wherein, referring to FIGS. 1 and 2, the common electrode layer 5 is divided into a plurality of touch control inductive electrodes 5a that are distributed in an array, a plurality of metal connection lines 6a are disposed in the third metal layer 6, and each touch control inductive electrode 5a is connected to a touch control detection chip 8 through an independent metal connection wire 6a. In specific, in order not to affect an aperture rate of a display area, the wiring direction of the metal connection line 6a is disposed to be the same as that of the data line, and a projection, of the metal connection line 6a located in the third metal layer 6, in the second metal layer 4 should be overlapped with the data line. Furthermore, the touch control inductive electrode 5a is electrically connected with the corresponding metal connection line 6a through a through hole (not shown in the figures) located in the third insulating layer 3c, and regarding a series of touch control inductive electrodes 5a, each metal connection line 6a is not connected with the previous touch control inductive electrode before being connected with the corresponding touch control inductive electrodes 5a, and the metal connection line 6a will not be continuously connected with the later touch control inductive electrode after being connected with the corresponding touch control inductive electrodes 5a. Wherein, since the common electrode layer 5 is also used as a touch control inductive electrode 5a, within a display time of one frame, the common electrode layer 5 (the touch control inductive electrode 5a) transfers common voltage (Vcom) and touch control signals in time-sharing.
As described in the above structure of the touch screen, a touch control sensitivity is relevant to a wiring resistance of the metal connection line 6a and a self capacitance of the touch control inductive electrode 5a, in order to avoid writing and reading a touch control pulse signal being affected by a signal delay, it needs to reduce the wiring resistance of the metal connection line 6a and a coupling capacitance formed between the metal connection line 6a and the touch control inductive electrode 5a. According to a formula for calculating the resistance: R=ρ×L/S, L denotes a length, S denotes a line cross section, p is a resistance rate, and S is in direct proportion to a wiring thickness and width. In the case where the length, thickness and resistance rate of the third metal layer 6 are not changed, in order to reduce effect on the touch control signal from the metal connection line 6a, if a width of a single metal connection line 6a is increased, the aperture rate of the display area will be reduced, and if a plurality of metal connection lines 6a are connected to one touch control inductive electrode 5a in parallel, a total wiring resistance value will be reduced, but increasing the number of the metal connection lines 6a will increase the coupling capacitance formed between the metal connection line 6a and the touch control inductive electrode 5a, and the touch control sensitivity also cannot be improved.
Thus, in structure of the in-cell touch screen, the problem desired to be solved is: how to reduce a resistance of a connection wiring of the touch control inductive electrode to improve the touch control sensitivity.